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A General Evaluation Framework for Topical Crawlers 总被引：10，自引：0，他引：10
Topical crawlers are becoming important tools to support applications such as specialized Web portals, online searching, and competitive intelligence. As the Web mining field matures, the disparate crawling strategies proposed in the literature will have to be evaluated and compared on common tasks through well-defined performance measures. This paper presents a general framework to evaluate topical crawlers. We identify a class of tasks that model crawling applications of different nature and difficulty. We then introduce a set of performance measures for fair comparative evaluations of crawlers along several dimensions including generalized notions of precision, recall, and efficiency that are appropriate and practical for the Web. The framework relies on independent relevance judgements compiled by human editors and available from public directories. Two sources of evidence are proposed to assess crawled pages, capturing different relevance criteria. Finally we introduce a set of topic characterizations to analyze the variability in crawling effectiveness across topics. The proposed evaluation framework synthesizes a number of methodologies in the topical crawlers literature and many lessons learned from several studies conducted by our group. The general framework is described in detail and then illustrated in practice by a case study that evaluates four public crawling algorithms. We found that the proposed framework is effective at evaluating, comparing, differentiating and interpreting the performance of the four crawlers. For example, we found the IS crawler to be most sensitive to the popularity of topics.Partially supported by National Science Foundation CAREER grant No. IIS-0133124/0348940. 相似文献
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VORA Aditya Mahabhai 《上海大学学报(英文版)》2008,12(4)
A well-known pseudopotential is used to investigate the superconducting state parameters (SSP), viz., electron-phonon coupling strength, Coulomb pseudopotential, transition temperature, isotope effect exponent and effective interaction strength for AgxZn1-x and AgxAl1-x binary alloys theoretically for the first time. We have incorporated here five different types of the local field correction functions to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of various exchange and correlation functions is concluded from the present study. Comparison with others such experimental values is encouraging, which confirms applicability of the model potential in explaining the superconducting state parameters of binary mixture. 相似文献
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Christiana Butera Priscilla Ring John Sideris Aditya Jayashankar Emily Kilroy Laura Harrison Sharon Cermak Lisa Aziz‐Zadeh 《Mind, Brain, and Education》2020,14(3):243-254
Difficulty processing sensory information may impede progress in school for students with autism spectrum disorder (ASD). We explore the relationship between sensory processing and school performance in 26 high‐functioning youths with ASD and 26 controls (age 8–14) using measures of sensory, social, cognitive, and academic functioning. In the ASD group, bivariate Pearson correlations indicated a significant positive relationship between intelligence quotient (IQ) and the School Competence Scale (SCS) of the Child Behavior Checklist (CBCL), and a significant negative relationship between Dunn's Sensory Processing Framework and SCS scores. Final hierarchical multiple linear regression model accounting for SCS scores in ASD included IQ, ADHD symptoms, and sensory features. An interaction between increased sensory sensitivity with reduced sensory avoidance behaviors explained the greatest amount of variance in SCS, meaning school performance is lowest for children with greater hypersensitivity and fewer avoidance behaviors. Results indicate a strong impact of sensory processing on school performance in ASD. 相似文献
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Abana, a herbal preparation of Himalaya Drug Co. significantly increases HDL—cholesterol and lowers LDL—cholesterol. Moreover, it antagonises the HDL lowering effect of metoprolol. 相似文献
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A theorem, similar to Tellegen's theorem, but for networks having dual topologies, is developed. This theorem is used in the frequency domain to define a new network operation called “generalized dual transposition”, whose applications in network synthesis are discussed. Finally, it is used in the time domain to define a network called “dual adjoint” and its relation to dual and adjoint networks established. 相似文献
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